Zepp said:"Kiya", "kyup", "utz", "die", it's all the same. I tell new students who ask about yelling that they can shout "yabba-dabba-doo!" if they really want. (Haven't heard anyone try it though.)
Gee, I should try that one. Sounds better than pow. No, he said today that it is from a Korean 12 years ago. TW